1. Field of the Invention
The present invention relates generally to the field of object locator systems, and more specifically to systems which use a radio frequency to locate objects.
2. Discussion of the Prior Art
Many different radio frequency object locator systems exist for enabling people to locate a small number of misplaced objects, such as keys, television remote controls, telephones, purses, eyeglasses and the like. These known locator systems typically include several color-coded object tags, each of which can be attached to an object, such as a set of keys or a television remote control. Such systems typically include a base having a color-coded button associated with each color-coded tag. The base may have a space next to each of the buttons in which a user can enter text describing the object to which the associated tag is attached. A user can press the button on the base to find an object that has been misplaced, and the base emits a radio frequency signal which is specific to the tag attached to the object. The tag responds to the radio frequency signal by emitting an audible signal, such as a beep, allowing the user to locate the missing object. Such a system is described in U.S. Patent Application Publication No. 2002/0126010 to Trimble et al.
Known locator systems are not very robust and have not functioned well. In particular, the known systems only have the ability to find a small number of objects, typically up to about four. In addition, the range of operation of the known systems is limited to about 30 feet. Some of the known systems use different radio frequencies for each object to be located, or use a separate carrier modulation code for each object. Some of the known systems have a pre-programmed code that the base and tag use for identification. These configurations restrict the number of different tags that can be used. For example, U.S. Pat. No. 6,297,737 to Irvin utilizes a Bluetooth transceiver located in a mobile terminal such as a cellphone, which forms the master to a Bluetooth piconet. The system may include up to seven slave Bluetooth devices in addition to the master device. The slave Bluetooth devices may be tags that can be polled to emit an audible signal when knowledge of their location is desired. The tags may also transmit a “found” signal to the master device. While the master device can display on an LCD display that desired tag has been located, the user must track down the tag by listening for the audible signal emitted by the tag. The master device cannot give any indication of proximity to the object. Bluetooth operates in the 2.4 GHz frequency band, which is a government regulated and crowded frequency band. In addition, the number of tags that can be searched for this type of system is extremely limited because of the inherent limitation on the number of devices that may be used in a Bluetooth piconet.
Other systems have been proposed for the location of a larger number of items, such as document files. U.S. Pat. No. 5,798,693 to Engellener describes a system including a tag associated with each object, and a plurality of interrogation signal generators. The signal generators are placed in each room or area of a user's premises, which may be a store or office, and can be caused by a central controller to poll each object tag located within their immediate vicinity. Each tag can include a unique identification code, and may include a resonance circuit that can emit a responsive signal to the signal generators. In another example, U.S. Pat. No. 5,689,238 to Cannon, Jr. et al. describes a system in which an electronic object tag is identifiable by a unique response code. The response code may be keyed into a portable interrogator by a user, which emits a radio frequency signal including the response code of the desired tag. The tag modulates its reflection of the interrogator's radio signal to allow the interrogator to indicate its relative proximity to the tag. Location markers may be used to amplify the signals and to provide an indication of the location of the object. Notably, both of these described systems have very short ranges of operation, and hence require intermediate signal amplifiers to operate effectively.
The known systems have other disadvantages and limitations, including significant installation expense and operation difficulties. In particular, a user may not wish to constantly poll for the location of all objects having tags, but may wish to simply locate one particular object that is missing. In addition, different users need flexibility in identifying the objects to be located, because entering the tag identification code to locate an object is not intuitive to a user. It is time consuming for a user to have to look up the tag identification code for the object they wish to locate. In addition, the user may not have ready access to the list or database in which they have stored or listed the tag identification codes, further delaying the recovery of the lost object.
It is desirable to produce an improved object locator system, which allows the user a significant degree of flexibility in its set-up and use.